Limit Characters and packages concern

How do we limit the characters of the custom fields? They are not available in setting up the packages.

Also, we can make their website link not available if they are only getting free listing but they can always put it somewhere else like in the listing description. How do we avoid this?

Another thing, I set up the free package as 1 category only. If a business wants to be in two category they should do the paid listing but then they can always make another listing in the different category with slightly different name and address so they dont have to get the paid listing. Hopefully they wont but they will if the set up of the website will allow it.